The Science of Protein Ingestion and Muscle Protein Synthesis

If you train with intensity, are involved in the sports nutrition industry or have delved into nutrition in general, at some point or another you have probably heard the term “muscle protein synthesis” at least once along with the thought engrained in most of our heads that you need a protein shake right after you get done training. While many have heard of it and know it’s important, the fact is that most still don’t know exactly what it is or the rhyme and reason behind it. The purpose of this article is to briefly explain what muscle protein synthesis (often shortened to MPS) is, what role protein ingestion has and a few cool things that can amplify it.

What is MPS?

             Before we can dive into the nutritional aspect of muscle protein synthesis, we must first understand what it is and how it works. The body is full of lean muscle tissue and they are constantly being remodeled through continuous and simultaneous processes of protein synthesis and breakdown (also called turnover). This process serves to breakdown old proteins and help in synthesizing new ones to help maintain protein mass and quality. Muscle Protein Synthesis is the process in which the synthesis of muscle happens from protein ingested from diet. This occurs regardless of exercise at a rapid rate while the body is growing though adolescence and into young adulthood1.

The other obvious stimulus of this process is exercise. In instances such as running or cycling over a distance, the damage/stress is cumulative and the result of combined repetitive movements and are typically at a lower level of intensity in terms of muscle damage. On the other hand, activities such as resistance training place force directly on the muscle, resulting in a more significant impact and more damage happens in a shorter time span2.

Why Protein Is Crucial for Training

With a basic understanding covered, we can now explain that skeletal muscle is constantly breaking down and synthesizing protein, with the rate increasing with exercise and if the body is to maintain its muscle mass, the net level of protein balance must equal zero. As one may imagine, for muscle mass to increase, muscle protein synthesis must exceed breakdown, so in the nature of this article let us look at the impact resistance training has on it3,4.

It has been shown in research that resistance exercise results in increased muscle net protein balance for 24–48 hours5. Both protein anabolism and catabolism increase after exercise, but the increase in anabolism is relatively larger, causing the net muscle protein balance to be positive. However, though while there is a great stimulation of MPS, without the presence of exogenous amino acids, the net protein balance remains negative, directly pointing to another key point that is crucial to this article: the effect of nutrition. In one particular study, it was found that with resistance training between 2 groups for 12 weeks, it was shown that a control group receiving no nutrition for 2 hours post-exercise decreased lean body mass while those consuming protein immediately after exercise increased lean mass6.

This clearly demonstrates the importance and synergistic effect of resistance exercise and amino acid ingestion to provide the requisite anabolic environment to support net tissue growth. Furthermore, one important thing that most never consider is that the degradation of the muscle due to strenuous exercise will not reach its peak for immediately following exercise in the affected the muscle. This means that not only it is important to consume protein in the aforementioned time frame after training, but to continue the ingestion of protein on a consistent, daily basis. The maintenance of consistent dietary practices is essential to the body's ability to respond on an ongoing basis to the demand for muscle protein synthesis, both from daily protein turnover and from exercise7.

Cut and dry, there has been a lot of research on the topic of what is ‘optimal’ and how to maximize muscle protein synthesis. The consensus has been that the ingestion ~0.31 g/kg of protein whereas muscle protein breakdown has been demonstrated to be maximally suppressed with a moderate insulin response (~30 g of carbohydrate) in the post workout recovery period8. One thing that we have been trying to capitalize on is this maximization of MPS via protein ingestion and insulin response. Enter a cool ingredient that I’m building into a few formulas myself called Velositol? from Nutrition 21, a chromium/amylopectin complex that increases muscle protein synthesis (MPS) when combined with protein and exercise.

With the knowledge of how protein (and the amino acid leucine primarily) stimulates MPS and is further driven by the hormone insulin, Velositol? has been shown to improve insulin action, as well as increase the metabolism of nutrients overall. This increase in the action of insulin causes increases in the metabolism of nutrients and increases in the rate of glucose and amino acid uptake in muscle cells. The initial studies done not only showed that Velositol? can amplify protein synthesis, even with smaller doses of protein, in this case 6g. In the study, the inclusion of Velositol? was able to nearly double the rate of MPS vs. whey protein ingestion alone9.

Another preclinical study conducted with rats to study the effects of larger protein amounts had the subjects dosed with whey protein (from 6g to 40g human equivalents), pea protein (6g human equivalent), or BCAA (6g human equivalent) with or without Velositol (2g human equivalent). It was shown in the study that after treadmill exercise, the Velositol? plus protein groups showed significantly greater MPS in muscle compared to the corresponding protein alone groups. At the larger protein doses, while the MPS wasn’t double like it was in the previous 6g human study, there was still a significant increase showing very promising potential for the amplification of protein synthesis. Though pre-clinical, it certainly is a promising step for the potential mechanisms that Velositol? could take advantage of in the formulation side of sports nutrition.

Wrapping Up

             In today’s article, we covered briefly what is muscle protein synthesis, what factors increase or decrease the rate at which it happens, the role exercise has on it, the importance of protein ingestion following training and last but not least a quick examination of the ingredient Velositol? in the amplification of muscle protein synthesis. This is a very broad and topic in which much more could be discussed such as maximum protein intake, types of protein ingested, etc. but we will revisit that another day. Until then, crush those weights, eat your protein and stay healthy!

REFERENCES

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2.          Atherton P. Muscle protein synthesis in response to nutrition and exercise. J Phys. 2012;590(5):1049-1057. doi:10.1113/jphysiol.2011.225003

3.          Millward D. The relative importance of muscle protein synthesis and breakdown in the regulation of muscle mass. Biochem J. 1976;156(1):185-188. doi:10.1042/bj1560185

4.          Anthony T. Mechanisms of protein balance in skeletal muscle. Domest Anim Endocinol. 2017;56(Suppl):S23-32. doi:10.1016/j.domaniend.2016.02.012

5.          Phillips S. Mixed muscle protein synthesis and breakdown after resistance exercise in humans. J Phys Endrocin Metab. 1997;273(1):E99-107. doi:10.1152/ajpendo.1997.273.1.E99

6.          Esmarck B. Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. J Phys. 2004;535(1). doi:10.1111/j.1469-7793.2001.00301.x

7.          van Vilet S. Achieving Optimal Post-Exercise Muscle Protein Remodeling in Physically Active Adults through Whole Food Consumption. Nutrients. 2018;10(2):224. doi:10.3390/nu10020224

8.          Glynn E. Muscle protein breakdown has a minor role in the protein anabolic response to essential amino acid and carbohydrate intake following resistance exercise. Regulatory, Integrative and Comparative Physiology. 2010;299(2):R533-40. doi:10.1152/ajpregu.00077.2010

9.          Ziegenfuss T. Effects of an amylopectin and chromium complex on the anabolic response to a suboptimal dose of whey protein. Journal of the International Society of Sports Nutrition. 2017;14(6). doi:10.1186/s12970-017-0163-1